There’s no easier way to improve the sound quality of your iPod than to swap out the original Apple earbuds for something better. With the right ‘phones (and quality audio files, of course) the iPod is capable of producing truly excellent sound. To help you find the right step up the audio ladder, we’ve rounded up nine current in-ear-canal headphones (also known as “canalphones”). A complete discussion of what makes this kind of headphones unique is available in our in-ear-canal headphone primer, but the quick description is that canalphones fit down inside your ear canals and are designed to block most external noise.

Prices of the models reviewed here range from $25 to $350, and the range in sound quality is equally wide—though sound quality isn’t strictly proportional to price. Construction quality and included accessories also vary from one pair of canalphones to the next, though most manufacturers include, at the least, multiple sizes of eartips and some kind of carrying case. Other possible add-ins include cleaning tools, cable extensions, and adaptors for connecting the headphones to home stereos and airplane audio jacks. (None of the models tested here have controls for the iPhone and recent iPods, though some do have inline volume controls.)

I tested the various models using an iPhone 3G playing 256kbps AAC files ripped from CDs; equalization (EQ) and Sound Check features were disabled. The testing was conducted over a period of one month in a variety of settings, both noisy (on airplanes, in commuter trains) and quiet (a basement and a rooftop terrace), from Chicago to Japan. Here’s a look, in alphabetical order, at the models I tested.

AO Safety Blockade Noise Isolating Earbuds

Right off the bat, the $50 Blockade Noise Isolating Earbuds—made by a company, AO Safety, specializing in industrial safety products such as ear-protection equipment—stand out with eye-catching packaging, and bright yellow eartips. In the box are three identical pairs of silicone, triple-flange eartips, along with a fabric carrying bag. The Blockade’s eartips are claimed to provide 24dB of noise reduction, and an inline volume-control limits the headphones themselves to 91dB of audio output. The Blockade’s construction doesn’t seem as solid as most of the other headphones here, but that’s not a surprise given the relatively inexpensive price.

The Blockade’s tips are soft and comfortable, providing a good seal and the promised noise reduction. On the other hand, if your gut tells you not to expect exceptional sound from a company focused on workplace safety, in this case you’d be right. There’s nothing objectionable about the Blockade’s sound quality—it’s about what someone who’s never heard a good set of headphones might expect. But while the midrange frequencies are balanced, they’re also muted and distant, and the highs and lows both taper off significantly. Apple’s stock earbuds produce better overall sound, just without the Blockade’s noise isolation. The $50 price tag is relatively inexpensive for in-ear-canal headphones, but the sound quality isn’t as good as several other noise-isolating canalphones priced even lower. For example, the Memorex EB100s tested here cost half as much and have superior bass. And several canalbuds, such as Sennheiser’s CX300-II and Radius’ Atomic Bass Earphones, also offer better sound in this price range.

Comply NR-10

Comply’s $100 NR-10 ships in a simple black box that also includes a soft carrying case and one extra pair of soft-foam eartips. The NR-10’s construction doesn’t inspire confidence: the cables are thin, and there’s no reinforcement where the cables meet the earpieces. On the other hand, the inline volume control is a nice extra, and the foam eartips are noteworthy for their comfort. The tips are long, allowing for a good fit in a wide variety of ears, and provide plenty of noise isolation. (Comply actually makes a line of these eartips for other brands and models of canalphones; Dan Frakes covered them last fall. The tips even come as standard equipment on some canalphones from other vendors, including the Westone model covered below. This makes comfort less of an advantage for the NR-10.) The headphones themselves are as understated as the packaging—black with the signature gray tips.

Comply claims noise reduction of 48dB or better, but in my testing the isolation seemed no better or worse than any of the other canalphones here. Audio quality is somewhat veiled and distant, similar to that of the Blockade model, but with noticeably better highs and lows. Still, there’s none of the sparkle, detail, or texture that one gets in better (and pricier) headphones. Overall, audio is roughly comparable to that of Apple’s stock earbuds, but with the benefit of sound isolation and stronger bass response. The inline volume control adds a bit of weight to the cables, and as no shirt clip is provided, that weight pulls directly on the eartips in your ears.

Etymotic Research hf5 High-Fidelity Earphones

Etymotic Research’s $150 hf5 High-Fidelity Earphones, available with black, red, or blue earpieces, include a full array of accessories: three pairs of eartips (foam, gray silicone triple-flange, and clear silicone triple-flange), an extra pair of filters, a cleaning tool, and a semi-soft carrying case. (The filters help keep moisture and ear wax from finding their way into the inner workings of the 'phones; Etymotic claims the filters also smooth the sonic output.) The headphones themselves are very light, the cable is rubbery and kink-resistant, and there's a slider to snug the cable under your chin and a small clip to secure the cable to your shirt.

In my testing, comfort and fit were exemplary—the hf5s slid right in, effortlessly creating a good seal, and their light weight and small size made them very comfortable, even for extended listening periods. The hf5’s audio is detailed and accurate, but leans toward the bright/forward end of the spectrum thanks to understated bass response. When pushed to higher volumes, this bright sound can become a bit strident, especially with some female vocals. But if you want comfort for long listening sessions, and don’t need loud volume and bass output, the hf5 are a very good choice, providing quality sound at a very reasonable price.

Future Sonics Atrio

Future Sonics’ $199 Atrio canalphones are well-built, with a very sturdy cord, and each set comes with a variety of sizes of foam and flanged-silicone eartips, a semi-hard carrying case, and a cleaning tool. Future Sonics claims Atrios can be worn either with the cable trailing down from the ear, or with the cable going up and over the top of the ear and then down behind; in the latter case, you use a slider to gather the left and right cables together behind your head. However, I was able to get the headphones to fit well only in the cable-up orientation, as the shape of the earpieces prevented me from inserting them far enough into my ears in the cable-down position. Which was fine, as I able to get a nice seal cable-up, and with the cable cinched against the back of my head, extraneous cable noise disappeared. Oddly, neither earpiece has any left/right label, leaving you to figure out from the shape which earpiece goes in which ear. (It appears, in my testing, that the cable-up orientation requires you to flip the left and right channels.)

The earpieces are available in four colors—black, blue, red, and “earth beige”—none of which, in my opinion, makes them attractive. But that ugliness is only skin deep: these are good headphones. Future Sonics makes much of its one-driver philosophy, holding that multiple drivers are unnecessary for good sound in canalphones, and the Atrios provide compelling evidence for that position. The first thing you notice is the bass response. It’s not especially tight or punchy, but it’s clean, real, and extended—all rarities in canalphones. In fact, there may be too much bass for some tastes, and on some recordings the prodigious bass response can overpower the Atrios's clean and clear mids and highs. Voices are natural and the highs are even cleaner (if less forward) than those of the Etymotic hf5. The Atrios headphones are not very efficient, requiring your iPod’s volume to be turned up a bit, but as with most canalphones, volume is easily loud enough to damage your hearing without distortion. The Atrios’s fit is a bit unconventional, but if bass response is important, these could be your ideal headphones under $200.